There are several distillation schemes in aromatics complexes that use a partial condenser for separation of lighter components. Typical examples of such columns include a C5 stabilizer or a dehepatnizer column.
FIG. 1 represents a prior art system 10 of a conventional C5 stabilizer 12. This conventional stabilizer aims at separating C1-C4 components as an overhead vapor product 14, C5 as an overhead liquid product 16, and C6+ components 18 as the bottoms product of the column. The column operates at 8.5 kg/cm2 g with an overhead temperature of 40° C.
However, the prior art system of FIG. 1 possesses several disadvantages. It is not possible to condense the lighter components 14 in the overhead product at 8.5 kg/cm2 g and use cooling water as the overhead cooling media. The overhead system has a partial condenser 20. Lighter components (used as offgas) are drawn as the vapor product 22 from the partial condenser 20. C5 liquid product 16 is the liquid stream from the partial condenser 20. A considerable amount of C5 components is lost to the offgas vapor stream. The loss of C5 components can be prevented by decreasing the overhead temperature (e.g., by using refrigeration) or increasing the column pressure. However, this increases the operating cost of the column. Prior art systems, such as the prior art system of FIG. 1, provide a loose split between C1 to C4 in vapor and C5 in liquid product. Recovery of these components is also low as they are lost in the offgass vapor stream 22.
FIG. 2 represents a prior art system of a conventional dehepatnizer column 30. This conventional dehepatnizer aims at separating lighter components (C1 to C5) as an overhead vapor product 32, C7 as an overhead liquid product 34, and C8+ components as a bottoms product 36 of the column. The column operates at 5.0 kg/cm2 g with an overhead temperature of 40° C.